• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.6
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• pp.73-80
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• 2006

Recently, Sun et el. proposed a three-party authenticated key exchange protocol using the public key of the server and the derived verifier from the Password of a user. This paper proposes a password-based three-party authenticated key exchange protocol using smartcards. Since the proposed protocol has very low computation cost by using XOR and hash function operation instead of the public key operation, and reduces the count of message transmission to 20% compared with the protocol of Sun et el., it can execute an effective authenticated key exchange. Furthermore, the proposed protocol is safe from password guessing attack by not saving passwords in the server, and it is also safe from server compromise attack because the server cannot know the shared session key between the two users.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.949-952
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• 2005

RS 시스템의 가장 큰 특징은 일대 다수의 그룹 및 지령 통신방식이다. TRS 시스템의 구성은 여러개의 그룹으로 구성되며, 각 그룹은 업무내용에 관련된 유사한 목적을 가진 사용자들의 단말기로 구성된다. 다양한 형태의 공격에 노출될 수 있으며, 대규모 통신을 위한 키 분배 혹은 설정에 많은 문제점을 가질 수 있다. 본 고에서는 TRS 상에서 안전한 통신을 수행하는데 있어 필수 요소인 회의용 키 분배 방식을 고찰한다. 본 방식은 통신 회수를 줄이면서도 사용자 인증을 수행할 수 있는 효율적인 Tree 기반의 회의용 키 분배 방식을 제안한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.5
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• pp.37-43
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• 2002

This paper proposes a password-based mutual authentication and key agreement protocol, which is designed by applying ECDSA and ECDH. The proposed protocol, AKE-ECC, computes 2 times of point multiplication over ECC on each of client and server, and generates the key pairs(public key. private key) and a common session key using ECDH that is different compare to previously proposed protocol. It is against common attacks include a dictionary attack and the security of proposed protocol is based on the ECDLP, ECDH.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.39-47
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• 2005

This paper proposes and analyzes the MAC(Message Authentication Code) algorithm that is used for the transition integrity and the entity authentication of message. The MAC algorithm uses the DES algorithm which has 64-bit block and 56-bit key and we compare the security according to 64-bit and 32-bit length of MAC value. Moreover, we use the SEED algorithm which has 128-bit block and 128-bit key and compare the security according to 128-bit and 64-bit length of MAC value. We analyze the security the forgery attack according to length of message and length of MAC value. this paper, a coarse-to-fine optical flow detection method is proposed. Provided that optical flow gives reliable approximation to two-dimensional image motion, it can be used to recover the three-dimensional motion. but usually to get the reliable optical flows are difficult. The proposed algorithm uses Horn's algorithm (or detecting initial optical flow, then Thin Plate Spline is introduced to warp a image frame of the initial optical flow to the next image frame. The optical flow for the warped image frame is again used iteratively until the mean square error between two image sequence frames is lowered. The proposed method is experimented for the real moving Picture image sequence. The proposed algorithm gives dense optical flow vectors.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.3 s.309
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• pp.10-19
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• 2006

In this paper, we propose 128-bit chaotic block encryption scheme using a PLCM(Piecewise Linear Chaotic Map) having a good dynamical property. The proposed scheme has a block size of 12n-bit and a key size of 125-bit. The encrypted code is generated from the output of PLCM. We show the proposed scheme is very secure against statistical attacks and have very good avalanche effect and randomness properties.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.406-414
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• 2005

In this paper, we propose 128bits chaotic block encryption scheme using a PLCM(Piece-wise Linear Chaotic Map) having a good dynamical property. The proposed scheme has a block size of 128 bits and a key size of 128 bits. In proposed scheme we use four 32bi1s sub-keys of session key and four 32bit sub-blocks of block to decide the initial value and the number of iteration of PLCM. The encrypted code is generated from the output of PLCM. With results of test and analyses of security we show the proposed scheme is very secure against statistical attacks and have very good Avalanche Effect and Randomness properties.